ADU rules in Buncombe County, NC β also called accessory dwelling unit regulations or granny flat ordinances β cover setbacks, owner-occupancy, parking, and permit requirements.
Unincorporated Buncombe County (the Asheville area outside city limits) is unusually permissive for accessory dwelling units. Chapter 78 of the Code of Ordinances allows 'two residential dwelling units (attached or detached)' as a use by right in every residential and open-use district (R-LD, R-1, R-2, R-3, OU), letting most homeowners add a second full home or detached ADU on a single lot without rezoning. Accessory structures used as ADUs must follow Β§78-663 standards. North Carolina Session Law 2025 (S495) further mandates that local governments allow at least one ADU per single-family lot for permit applications filed on or after October 1, 2025.
Buncombe County's zoning is governed by Chapter 78 of the Code of Ordinances (Municode). The county's residential and open-use districts each list 'two residential dwelling units (attached or detached)' among their permitted uses by right: R-LD Low-Density Residential, R-1 Residential (single- and two-family), R-2 Residential, R-3 Residential (which also allows multifamily where utilities are available), and the OU Open Use district where most uses are allowed by right. This means a property owner in unincorporated Buncombe County can typically build a second home or a detached accessory dwelling on the same lot without a special use permit, as long as both units satisfy the lot-size and setback rules in Β§78-642 (dimensional requirements) for the underlying district. Section 78-662 caps a single lot at four principal buildings plus customary accessory buildings, with exceptions for planned unit developments and places of worship. When an ADU is built as a detached accessory structure, Β§78-663 controls placement: smaller accessory buildings (320 square feet or less and 15 feet tall or less) require 7-foot side and rear setbacks, while larger accessory structures (more than 320 sf or taller than 15 ft) need 7-10 foot side setbacks (depending on whether public sewer is available) and a 10-foot rear setback; front setbacks follow the underlying district. If the existing primary structure is legally nonconforming on front setbacks, accessory buildings may match that line. Accessory uses cannot include any use that is otherwise prohibited or that would itself require a special use permit. Travel trailers and recreational vehicles cannot serve as ADUs in residential districts. On top of these local rules, North Carolina Session Law S495 (2025-2026 session, applicable to permit applications submitted on or after October 1, 2025) requires every local government to allow at least one ADU that conforms to the NC Residential Code per single-family detached dwelling in residential zones, prohibits parking minimums tied to the ADU, and bars maximum unit sizes below 800 square feet; local governments must adopt conforming regulations by January 1, 2027 or ADUs default to no local limitations. Buncombe County's existing 'two-units-by-right' framework already meets the core S495 mandate. Building permits, zoning permits, and septic/health-department approval (where public sewer is unavailable) are issued by the Buncombe County Planning & Development Department; the City of Asheville, Town of Black Mountain, and other municipalities have their own zoning ordinances that are not covered by Chapter 78.
Building a second dwelling, an accessory apartment, or a detached ADU without a zoning and building permit violates Chapter 78 and the NC State Building Code. Enforcement is handled by Buncombe County Planning & Development through stop-work orders, denial of certificate of occupancy, daily civil penalties, and abatement actions authorized under N.C. Gen. Stat. Chapter 160D (the consolidated planning and development statute). Converting a permitted accessory building (garage, shed, barn) into living quarters without separate permits triggers code-enforcement action, since Β§78-663 limits accessory uses to those subordinate to the principal use and an unpermitted dwelling is not a 'customary' accessory use. The Buncombe County Board of Adjustment hears variance requests and appeals of zoning decisions; appeals from a zoning administrator's determination must be filed within 30 days under N.C. Gen. Stat. Β§160D-405. Using a travel trailer or RV as a dwelling in a residential district is prohibited and subject to abatement.
Buncombe County, NC
North Carolina bans consumer fireworks that fly, spin, or explode. In Buncombe County only ground-based sparklers, fountains, snakes, smoke devices, and tric...
Buncombe County, NC
Short-term rental rules in Buncombe County depend on whether the property sits inside Asheville city limits or in unincorporated Buncombe County, and the two...
Buncombe County, NC
Buncombe County, North Carolina enforces flood damage prevention under Chapter 34, Article II of the Buncombe County Code, administered by the Planning and D...
Buncombe County, NC
Buncombe County enforces the 2018 North Carolina Residential Code, Appendix NC-A (the NC adaptation of IRC AG105) for residential swimming pool, spa, and hot...
See how Buncombe County's adu rules rules stack up against other locations.
Help us keep this page accurate. If you notice an error or outdated information, let us know.